1. Field of the Invention
The present invention relates to a beverage extractor for extracting a beverage from a raw material, such as ground powder of coffee beans.
2. Description of the Related Art
One of the known beverage extractors of this kind is provided with a cylinder for accommodating a raw material, a piston disposed to be movable within the cylinder, a hot water feed pipe for feeding hot water into the cylinder and an extraction pipe for letting flow out the beverage extracted in the cylinder. With this extractor, regular coffee or espresso coffee is extracted by feeding the raw material, which is coffee beans ground to the grain size for either regular coffee or espresso coffee, into the cylinder, compressing the powder between pistons and feeding hot water into the cylinder.
In this beverage extractor, it is necessary to feed hot water into the cylinder, when regular coffee is to be extracted, under a pressure of 0.1 MPa to 0.3 MPa or, when espresso coffee is to be extracted, under a pressure of about 0.9 MPa. For this reason, it is necessary to keep the aperture of the extraction pipe channel smaller when espresso coffee is to be extracted than when regular coffee is to be extracted to keep the pressure of hot water to be fed into the cylinder at the required level.
However, since this beverage extractor uses a common extraction pipe for extracting regular coffee and espresso coffee and extraction of regular coffee with an extraction pipe suitable for the extraction of espresso coffee takes a much longer time because the hot water feeding pressure should be reduced. Taking a longer time to extract the beverage may invite excessive extraction of the content of the raw material and therefore degradation of the quality of the extracted beverage.